While not limited thereto, the present invention is particularly adapted for use with percussion tools such as fluid-operated hammers used in the construction and mining industries. In a hammer of this type, a piston is initially forced upwardly to compress a fluid in an accumulator chamber. Suitable valving then releases pressure from the underside of the piston, whereupon the stored energy of the compressed fluid in the accumulator forces the piston downwardly to impact against an anvil or the like.
In the past, most fluid-operated hammers of this type have utilized a gas accumulator. Hydraulic accumulators have also been proposed but such hydraulic accumulators heretofore have been quite large owing to the stiffness (bulk modulus) of the hydraulic fluid. As a consequence, and because of the large size of the required accumulator, all-hydraulic impactors have not found widespread use.